The subject invention is directed to the art of vascular catheters and, in particular, to methods and apparatus for the maintenance of clot-free catheter lumens in surgical procedures such as angiography.
As a general principal, in the field of angiography there is a constant need to maintain the lumen of a catheter continually filled or washed with a sterile solution such as a saline solution, or with an opaque media. This is done in order to reduce the possibility of blood entering the lumen and forming a clot therein. These clots are not easily seen forming and often impossible to detect. In the event that a clot does form, it could be inadvertently injected into the vascular system with disastrous results.
In performing the procedure of catheterization, there are a number of diverse functions which must be carried out by the surgeon using a catheter. These functions include monitoring the pressures within the vessels, injecting opaque media at a target site and providing a means to constantly flush or maintain the catheter at all times filled with saline solution to prevent clots when other media is not being injected through the catheter lumen.
To add to the above difficulties, many procedures require large amounts of opaque media to be rapidly injected into the target site. Frequently, to achieve this rapid injection, pressure at the proximal or hub end of the catheter often reaches 1,000 PSI. One explanation for the necessity of such high pressures and large volumes of opaque media flowed over a short period of time is that the vessels of an organ such as a kidney must be filled very quickly in order to obtain an X-ray image before the heart pumps the opaque dye media from the target site and into the body's vascular system. For certain procedures, one or two heartbeats are all that is necessary for the dye to be of little or no use at the target site for imaging purposes.
Angiographic catheters such as described in my earlier U.S. Pat. No. 3,503,385 and my co-pending U.S. application Ser. No. 08/144,202 filed Oct. 27, 1993, the teachings of which are incorporated herein by reference, have been ruggedized or otherwise designed to withstand the high pressures mentioned above. However, heretofore, it has been difficult or nearly impossible with existing equipment to ensure that sterile saline solution continuously flows through the catheter lumen substantially immediately after the dye injection in order to keep the lumen flushed at all times to prevent clots.
One prior art method and apparatus used to control the saline fluid has involved a stopcock which is manually operated as fast as possible in order to quickly gate the saline flow on and off. However, given that there are often a plurality of stopcocks mounted on a single manifold to control other catheterization functions such as connections to pressure monitoring equipment or the like, surgeons find it difficult to first locate and then operate the correct stopcock in typically hurried moments of a catheterization procedure. Further, in the urgency or quick pace of a catheterization, it is possible to overlook whether all of the stopcocks mounted to a manifold are properly opened or closed. In some catheterization functions such as pressure monitoring, a stopcock which inadvertently remains closed becomes immediately obvious. This is not so with the saline line used in catheterization. It could be disastrous if the saline line is permitted to remain closed after the dye is injected for the reasons stated above.
Therefore, it is desirable to provide a simple and reliable method and apparatus to ensure that the saline line supplying a catheter assembly is operated automatically. This method and apparatus should preferably provide a solution which reduces the number of personnel responsibilities and patient risks associated with catheterization procedures such as angiography.